Computer network anf Http protocol

8/20/2019 Computer network anf Http protocol

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HTTP ProtocolInstructor: Prof. Dr. Friedbert Kaspar

Mai Nam Chuong

!" #I$ %&'% ( Computer Net)or*s


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∗De+nitions

∗HTTP Communication chain

∗HTTP Transport binding

∗HTTP Methods

∗HTTP Messages

∗HTTP $tatus Codes

∗HTTP Caching

∗,-

genda

%


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∗

set of rules and regulations thatdetermine ho) data istransmitted.

Communication Protocol/

0


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1 2$I la3ers

HTTP4 $MTP4 FTP4

DN$5

6


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∗

pplication 7s. pplication la3er∗ pplication la3er pro7ides ser7icesfor user applications to use. 2r4

∗ "ser applications use protocols that

reside at the application la3er.∗ 89: Internet 89plorer ( HTTP 2utloo*

( $MTP

pplication la3er/

;


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∗H3perte9t Transfer Protocol∗ an applicationFC


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HTTP protocol/

1


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∗

Histor3∗ 'BB& ( HTTPA&.B∗ 'BB? ( HTTPA'.&

∗ 'BBB ( HTTPA'.'

∗ Ne9t HTTPA%.& =draft@

HTTP protocol/


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∗ The HTTP protocol is areuestAresponse protocol

∗ client sends a reuest to theser7er

∗ The ser7er responds data

HTTP Communication

chain

>euest

>esponse

HTTP Client HTTP $er7erB


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∗HTTP >euestA>esponse Chain

)ith Intermediaries

HTTP Communication

chain

>euest

>esponse

HTTP ClientHTTP $er7erIntermediar3

>euest

>esponse

Pro93!ate)a3

'&


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∗Do not remember pre7iousreuestAresponse chain

HTTP stateless protocol

>euest '

>esponse '

HTTP Client HTTP $er7er

>euest %>esponse %

Ho) to maintain state/

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∗ Transitor3 connection∗ 2ne connection is created for each

reuestAresponse

∗Persistent connection

∗ The connection is *ept open after eachreuestAresponse set until the client isdone reuesting all the documents.

HTTP Transport binding

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∗GET < >euests data from aspeci+ed resource

∗POST < $ubmits data to beprocessed to a speci+ed resource

HTTP !8T 7s. P2$T

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HTTP !8T 7s. P2$T

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∗Communication bet)een de7icesusing the HTTP ta*es place7ia HTTP messages

∗ T)o t3pes:requests and responses.

∗ Te9t


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HTTP >euest Message

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∗Host:

∗$peci+es the Internet host

∗Host: ))).7gu.edu.7n:&&

∗User-A!ent∗$peci+es )hat agent =application@ is sending thereuest

∗"ser


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HTTP >esponse Message

%&


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∗Ser%er

∗ $er7er info that ser7es the reuest∗ $er7er: pacheA%.6.' ="ni9@

∗E&pres∗ gi7es the dateAtime after )hich the response is

considered

∗ 89pires: Thu4 %& ul %&'0 '?:&&:&& !MT

∗Re$resh∗ "sed in redirection4 or )hen a ne) resource has been

created.

∗

>efresh: ; urlJhttp:AA))).7gu.edu.7n

HTTP >esponse Headers

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∗'&& (In$oratona) >euest recei7ed4 ser7er is

continuing the process.∗+&& (S"ccess): The reuest )as successfull3

recei7ed4 understood4 accepted and ser7iced.

∗,&& (Redrecton): Further action must be ta*en inorder to complete the reuest.

∗&& (Cent Error): The reuest contains bad s3nta9or cannot be understood.

∗.&& (Ser%er Error): The ser7er failed to ful+ll anapparentl3 7alid reuest.

HTTP $tatus codes

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∗+// O0 : The reuest is ful+lled.

∗,/' 1o%e Peranent2: Theresource reuested for has beenpermanentl3 mo7ed to a ne)

location∗,/ Not 1od3ed: $er7er noti+es

that the resource reuested has notbeen modi+ed.

Common HTTP $tatus

codes

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∗// 4ad Re5"est: $er7er could notunderstand the reuest =s3nta9 error@.

∗/' A"thentcaton Re5"red: Thereuested resource is protected4 andreuire clientLs credential.

∗/, 6or7dden: $er7er refuses tosuppl3 the resource4 regardless ofidentit3 of client.

∗/ Not 6o"nd: The reuested

resource cannot be found in the ser7er.

Common HTTP $tatus

codes

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∗.// Interna Ser%er Error: $er7er iserror in the ser7er


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∗Cache: local cop3 of a resource

HTTP Caching

>euest

>esponse

HTTP ClientIntermediar3

>euest

>esponse

HTTP $er7er

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∗alidation Model∗ hen the resource last changed/

∗ 8liminate full response to client

∗ >educe net)or* band)idth

∗ If


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∗>FC


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Computer network anf Http protocol